Practical Insights and Safety Tips for URLs

What Is a URL (Uniform Resource Locator)?

A URL, short for Uniform Resource Locator, identifies the location of a file on the internet and enables users to access that content via web browsers.

• This includes not only web pages, but also images, videos, documents, and software files stored on remote servers.
• Unlike local files that are opened with a click, web-based content requires a URL to guide your browser to the correct destination on the network.

For example, entering a URL into a browser’s address bar allows the browser to fetch and display a web page, similar to opening an HTML file locally by clicking on it.

Other Names and Pronunciation

URLs are often referred to as website addresses, especially when they start with HTTP or HTTPS.

• These types of URLs point to websites using the Hypertext Transfer Protocol, which is the most common method of communication on the web.
• The term URL was originally known as Universal Resource Locator before it was changed in 1994 to its current definition.

The term is commonly pronounced by spelling out the letters—U-R-L—rather than as a single word.

Common Examples of URLs

You’ve likely typed a URL like https://www.google.com to access a website.

• This full string is the complete web address, or URL, guiding your browser to the site’s home page.
• Other examples include https://www.lifewire.com and https://www.microsoft.com.

URLs can also link directly to specific files like images.

• For example, a URL to Google’s logo on Wikipedia:
  https://upload.wikimedia.org/.../Google_2015_logo.svg.png
• This URL includes multiple folders and filenames, pointing precisely to where the image is hosted.

You can even use IP addresses as URLs to access devices like routers, with examples like http://192.168.1.1 used for network settings.

Protocols Used in URLs

The most common protocol is HTTP, but others like FTP, MAILTO, TELNET, and RDP are also valid.

• Each protocol is used for different types of tasks, such as file transfer, email links, or remote desktop access.
• URLs can even be used to open local files with specific protocol settings.

Structure of a URL

A standard URL has multiple components, each serving a specific purpose in directing you to the correct content.

Using the URL:
https://security.googleblog.com/2018/01/todays-cpu-vulnerability-what-you-need.html
Here’s the breakdown:

• https is the protocol, identifying the communication method.
• security is a hostname, a subdomain used for accessing a specific section.
• googleblog is the domain name, showing the service or entity hosting the content.
• .com is the top-level domain (TLD), indicating the domain category.
• /2018/01/ refers to directories, which act like folders organizing the server content.
• todays-cpu-vulnerability…html is the specific file the browser requests.
• The full section security.googleblog.com is called the Fully Qualified Domain Name (FQDN).

URL Syntax Rules

URLs are limited to letters, numbers, and a few special characters: ()!$-'_*+.

• Any other characters must be encoded into a format browsers can interpret.
• For example, a space becomes %20 or sometimes a +.

URLs often contain parameters, introduced by a ?, to pass data to the website.

• A search query like https://www.google.com/search?q=lifewire uses ?q= to send the search term to Google’s server.

When multiple parameters are used, they are separated by ampersands (&).

• In this Amazon search:
  https://www.amazon.com/...&field-keywords=windows+11, the second variable follows &.

Anchors, marked with a #, allow navigation within a page.

• For example: https://en.wikipedia.org/wiki/Lifewire#History jumps to the History section.

Everything after the domain in a URL is case-sensitive, so changing the case of a word in the path can result in a 404 error.

Display and Use of URLs

If a URL leads to a viewable file like a JPG, it opens in your browser; if not, the browser will prompt a download.

• This applies especially to file types like DOCX or EXE, which aren’t displayed natively.

URLs are a human-readable substitute for IP addresses.

• This translation is handled by DNS servers, making websites easier to remember.

Incorrectly typed or malformed URLs may return 400-series errors, especially 404 (Not Found) errors.

• Some websites even use custom 404 pages to entertain or guide users.

Clicking suspicious or shortened URLs may expose you to phishing or malware.

• Use link preview tools to verify the destination before clicking unknown links.

Ports in URLs

Most URLs don’t display port numbers, but sometimes they are specified like google.com:80.

• This happens when a site uses a non-standard port, such as 8080 instead of the default 80 for HTTP.

For FTP connections, the default port is 21, though it can vary, and must be included in the URL if changed.

Frequently Asked Questions

Can I block a URL?
Yes, you can block specific URLs via browser settings or your router’s configuration page.

What is a vanity URL?
A vanity URL is a custom, simplified address that redirects to a more complex URL, often used in branding.

What is a callback URL?
A callback URL is the return destination after a user finishes a task on another site, like confirming a payment.

What’s the difference between HTTP and HTTPS?
HTTPS encrypts data for secure communication, making it essential for sites handling sensitive information.